三种方式供你选择
- 通过KVC来设置
- 通过runtime动态改变
- 通过 msg_send() 设置
例子:
有这样一个类 PrivateVariablesClass:
@interface PrivateVariablesClass ()
@property (nonatomic, assign) NSInteger priviteNum;
@property (nonatomic, strong) UIView *priviteView;
@end
@implementation PrivateVariablesClass
-(void)showPropertyPrivateVariablesClass
{
NSLog(@"priviteNum = %@", @(_priviteNum));
NSLog(@"priviteView = %@", _priviteView);
}
我们在外部改完后,调用 showPropertyPrivateVariablesClass 方法去查看这两个私有属性的值。
1.KVC:
-(void)way1{
PrivateVariablesClass *classA = [[PrivateVariablesClass alloc] init];
[classA setValue:@(4) forKey:@"_priviteNum"];
[classA setValue:self.view forKey:@"_priviteView"];
[classA showPropertyPrivateVariablesClass];
}
控制台打印:
2019-03-04 15:37:05.962204+0800 私有变量传值[45878:581429] priviteNum = 4
2019-03-04 15:37:05.962745+0800 私有变量传值[45878:581429] priviteView = <UIView: 0x7ff224f06590; frame = (0 0; 375 667); autoresize = W+H; layer = <CALayer: 0x60000378e2a0>>
2.通过runtime动态改变
-(void)way2{
PrivateVariablesClass *classA = [[PrivateVariablesClass alloc] init];
unsigned int outCount = 0;
Ivar *ivars = class_copyIvarList([PrivateVariablesClass class], &outCount);
for (int i = 0; i < outCount; i ++) {
Ivar ivar = ivars[i];
const char *ivarName = ivar_getName(ivar);
//这里要注意ARC下, 这个会报错
/**
在修改NSInteger型变量的时候,ARC下,编译器不允许你将NSInteger类型的值赋值给id,在buildsetting中将Objective-C Automatic Reference Counting修改为No即可。但是这样工程就会变成MRC,所以,如果是非对象类型就不建议用object_setIvar这样的方法去修改了。
*/
int a = strcmp(ivarName, "_priviteNum");
if (strcmp(ivarName, "_priviteNum") == 0) {
//这种方式传值int类型会报错,不能传入
object_setIvar(classA, ivar, 22);
}
if (strcmp(ivarName, "_priviteView") == 0) {
object_setIvar(classA, ivar, self.view);
}
}
[classA showPropertyPrivateVariablesClass];
}
控制台输出结果:
2019-03-04 15:38:25.938643+0800 私有变量传值[45895:582713] priviteNum = 22
2019-03-04 15:38:25.939206+0800 私有变量传值[45895:582713] priviteView = <UIView: 0x7f85675057d0; frame = (0 0; 375 667); autoresize = W+H; layer = <CALayer: 0x6000018c0140>>
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3.msg_send() 去修改 (适用私有属性,不适用私有变量)
既然是私有属性了,必然有setter方法, 那我们动态调用一下。
-(void)way3{
PrivateVariablesClass *classA = [[PrivateVariablesClass alloc] init];
((void (*)(id, SEL, int))(void *) objc_msgSend)((id)classA, @selector(setPriviteNum:) , 33);
((void (*)(id, SEL, id))(void *) objc_msgSend)((id)classA, @selector(setPriviteView:) , self.view);
[classA showPropertyPrivateVariablesClass];
}
控制台输出结果:
2019-03-04 15:40:13.489726+0800 私有变量传值[45911:583616] priviteNum = 33
2019-03-04 15:40:13.490237+0800 私有变量传值[45911:583616] priviteView = <UIView: 0x7fd43ad21520; frame = (0 0; 375 667); autoresize = W+H; layer = <CALayer: 0x600003c78360>>